Throatless power saw of reciprocating blade type



Sept. 25, 1956 J. E. HAYDON 2,764,189

THRoATLEss POWER sAw oF RECIPROCATING BLADE TYPE Filed Sept.. 30, 1954 5 Sheets-Sheet 1 A ORNEYS Sept. 25, 1956 J. E. HAYDON THROATLESS POWER SAW OF' RECIPROCATING BLADE TYPE Filed Sept. 30, 1954 JOHN E. HAYDON, Q/M, hmm; l

Sept. 25, 1956 J. E. HAYDON THROATLESS POWER SAW OF' RECIPROCATING BLADE TYPE 65s sheetsheet :5

Filed Sept. 30, 1954 .a S RN 1 M O0 N MD R. EY awam VA T WH TA E ,Y NM

H O .IU FW Y w B uw M 2 6 :u i M 5% w m/ 5 5 A0 a,

United States Patent 'rHRoA'rLEss PowER saw 0F REIPRoCArING BLADE Tyra John E. Haydon, E drnonston, ibid. A pllitafion September 3.0, 1.9.54; Stdt!! No 59,923

11 Claims. (Cl. 14S-159) rThis invention relates to power saws and particularly *Sto one of the type in which the saw blade is reciprocated tor cutting. More especially the invention is concerned with a power saw of the reciprocating blade type which is throatiess that is, it can be employed to cut workpieces of unlimted lateral dimension.

Conventional saws of the `throatleoss type are well known, such saws for example being the common rotary buzz saw and the perhaps less common but well known saber saw. The latter, as does the saw of the present invention, involves a reciprocation of the saw blade for cutting. lboth rotary or buzz saw blades and saber saw blades are relatively expensive. ln the case of the former also, certain materials cannot be satisfactorily cut and the edges of the kerfs formed in workpieces thereby are usually poorly finished and rough. In addition, `the end of a cut made by a buzz saw is not square with the surface .of the material being cut. Hence corners cannot be cut out clean without .running into portions .of the workpiece that it may not be desirable to`cut. Aside from. the cost of saber s'aw r'blades, the fact .that in use they are supported but at .one end severely limits the various types of .materials with which .they `may be employed as ,well `as .the speed at .which cutting may be accomplished with them.

As indicated previously, my invention is concerned with a throatless shaw.` it therefore possesses the most important characteristic of buzz orrsaber type saws. It is free, however, from `all of Lthe disadvantages of those two types of saws as outlined above. lThu's`it can -be employed for cutting a wide variety of materials, it can uleave "a square ker end, it can operate at Vhigh speeds becauseQas will `.be explained below, l provide 'an upper end guide and backup for the blade, and perhaps most important of all it can employ conventional inexpensive hack saw blades. Iin addition, in my power saw the exposed portion of the blade during cuttingQt'hat is, the portion not lying in the l kerf of the".cut, is'carefully protected Aby an adjustable guard. The problemA of guarding `buzz sawand saber saw blades is one that has heretdfore presented `considerable diliiculty. v

A power saw according to my invention includesa conventional work supporting surface. A guide and "guard supporting fin extends upwardly yfronrtlie work `supporting surface.U The thickness'of th'ew'n'is' advantageously a@ ,greater than arefefally .las than the .tlifckiis f a :treff i@ 1b.@ farmed ia avatares@ bythe ist# A guide for the upper end of a conventional V'hackws'aw Vblade is supported by the iin. The hak 4Saw blade to belemployed `iriaybe `of conventional "form andis adapted to extend downwardly .ffomrthe' ,anida fhfoagh fhfirk supporting surface to a supporting member mounted therebelcw. The supporting member for the lower `@ad of the .saw blade is mounted for .reciprecation arid tti@ power .saw includes means for reciprocating the saw A sup- .ao and thereby fthe saw. .A .hlollvdowlll `manila,er for .neiging a workpiece in fifa sasasaasaf with the Vvantageously be supported by the n.

2,764,189 Patented Sept. 25, 1.956

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work surface during a sawing operation may also adi This hold-down member may also advantageously take the `form of a guard shielding the upper end of a saw blade from contact by' the operator. In addition the blade support and the guide for the upper end of the blade are advantageously so located relative to the n and the `fin is or such shape that it provides a backup support for the blade `during operation of the saw.

For a more detailed understanding of my invention, reference may be made to the following specific descrip.- tion of one form of saw coming within the SCOPe there or and to the accompanying drawings, .in which:

Fig. l is a front elevation of the saw;

Fig. 2 is a side elevation thereof;

Fig. 3 is an enlarged side elevation partly in section of the tin, guide and guard elements; and

Fig. ll is a sectional'view in plan taken along line 4 4 of Fig. 3.

Referring to the drawings, the power saw comprises a suitable supporting framework '10 which supports a dat `work supporting surface 11 of substantial area. A conventional hack saw blade 12 extends ,through an opening i3 (Fig. 3) in work surface 11 and is supported at its lower end beneath the work surface by a support member i4 (Fig. 2) which is reciprocably mounted on a guide l5 which in turn is supported from the framework by a bracket 16. The connection between blade i2 andsuppcrt member 14, as will be noted in the drawings, makes use of the hole in the end of the blade, this hole being one oi those conventionally found in the end of'haek saw blades. Support member 14 and hence the saw blade 12 are reciprocated by a connecting rod 13 secured at one end to the support member 14 and at its other end to a drive pulley i9 suitably mounted for ro"- tation in framework 16. Drive pulle;l 19 is driven by a lFil-belt 2l) extending between it and a pulley Zlmofunted on the output shaft 22 of a drive motor 23. `.On the other end of motor shaft 22 there is mounted a flywheel 24, the` function of which is conventional,` namely, to maintain the load on the motor nearly uniform. The motor 23 is preferably a variable speed motor, though it` desirable it may be a constant speed motorfin which case it will be advantageous to provide a variable speed transmission of one sort `or another (not shown) between the Aoutput shaft of `motor 23 and drive pulley 19. While the `direction of rotation of drive pulley is `not critical, l have found that for the best and smoothest operation of the saw, it should .be'rotated in a counterclockwise direction as seen in Fig. 2.

Byret'erence to Figs. 3 and 4 in particular, .it can be seen that the power saw includes a thin fin 30 supported from the framework 10 to extend a substantial distance `above work supporting surface lll. The n'tl is piovided with a vertically disposed forward edge 31 in close proximity to .which the rear edge of saw blade lZ'move's during reciprocation.' This edge of the iin provides, as heretofore suggested, a backup'v for the saw .blade during use. Hence when a workpiece is urged Vagainst the cut ting edge of the saw tending to force it rearwardly, it may engage and slide upon edge 31 of `the tin.

yA -pair of guide members 32'are` lixedly secured to the adjacent its forward edge 31 and extend .forwardly thereof. r-i`hese guide members, only one of which is shown in Pig. 3, are spaced from one another to accommodate movement or"l the saw blade therebetween and each contains a groove extending longitudinally thereof.` The two grooves are adapted to `form together a channel for a ball 33 which may be mounted in'fthe conventional opening 34 found Ain 'the' `end' ofthe'haek .ser .blas' Plvfiastacipi'acto ,Off the 'Saw blade '11.25

therefore, its upper end is firmly guided by guide members 32. A pin might be employed, of course, instead of ball 33, but I find that best results may be achieved `with the latter.

During use of my power saw for cutting a workpiece supported on surface 11, it is necessary during the upward stroke of the saw blade to positively hold the work down as it will otherwise be carried upwardly from the work supporting surface. I therefore provide what may be termed hold-down apparatus. As it is also desirable7 and for safety reasons essential, that the exposed portion of the saw blade be shielded, I also provide a shield or guard for this purpose. l have found it convenient to combine these two elements.

The hold-down and guard assembly comprises, as may be seen in Figs. 3 and 4, a pair of locking members 40, one on each side of iin 30. Each locking member 40 is provided with an elongated slot 41 adapted to receive therethrough a locking shaft 42. which is mounted in a circular hole 43 in iin 3f). Locking shaft 42 is threaded at its opposite ends and upon each carries a collar 44 rotatable thereon by a knurlcd knob 45. Locking plates 40 are free to move on locking shaft 42 except when urged firmly into engagement with tin 30 by collar members 44. This is accomplished when collars 44 are threaded onto shaft 4Z and irrnly engage locking members 40. A hold-down member Si) surrounds the saw blade and has rearwardly extending wing sections 51, each of which is secured on one side of fin 30 to a locking member 40 by screws 52. Hold-down member 50 has a planar lower edge parallel to work supporting surface 11. It further has an upstanding forward section 53 by which the portion of the blade 12 which is exposed immediately above a workpiece being cut is shielded from contact by the operato-r. The shape of upstanding portion S3 and that portion of hold-down member 5t) immediately thercbehind (to the left as seen in Fig. 3) is such that the operator can, however, peer around it to see the point of engagement of the cutting edge of the saw blade with the work. Furthermore, if desirable, the forward face of portion 53 of the hold-down member might be provided at its lowermost portion with a marker indicating the location of a saw blade therebehind.

A tubular guide enclosing member 60 is supported from hold-down member 50 by having downwardly extending flap-like portions 61, which are adapted to lie outwardly of hold-down member 50, secured thereto by screws or the like 62 (Fig. 2). It is also secured to the upper end of the forward upwardly extending portion 53 by a screw or bolt 54. Guide enclosing member 60 is provided at its upper end with flap closure 63 through which access to the guides 32 may be had for lubrication and other purposes.

Operation of the saw for cutting a given workpiece involves first a release of locking members 40 from a frictional locking engagement with fin 30 by a backing olf of collars 44 on shaft 42. The locking plates 40, tubular guide enclosing member 60 and hold-down member 50 may then be raised. The work is then placed on work supporting surface 11 and moved into engagement with the cutting edge of saw blade 12. The assembly of guide tube 60 hold-down member 50 and locking plates 40 is then lowered into engagement with the upper surface of the work and locked in this position by proper turning of locking collars 44 by means of knobs 45. The work is then advanced past the saw blade and past n 30 which enters the kerf cut in the work by the saw blade.

It will be clear that, as previously stated, the power saw of my invention is throatless, that is, workpieces of any lateral dimension may be cut thereby. It should further be clear from the above description that that portion of the saw blade extending above work supporting surface 11 which is not actually within the work being cut is completely protected by the forward portion 4 f 53 of hold-down member 50 and the tubular guide enclosing member 60. In addition, during operation the saw blade 12 is backed up by the forward edge 31 of n 30 whereby considerable pressure may be imposed on the blade by the work. In passing, it may be recalled that this is one of the chief disadvantages of a jig saw, for in such a saw there is no backup for the blade which is supported merely in tension. Of course one of the most important advantages of my power saw is in its ability to employ conventional hack saw blades which are relatively so inexpensive as heretofore pointed out.

Another advantageous feature of my power saw that has not heretofore been mentioned occurs in its use for cutting materials such as plastics which sometimes exhibit a tendency to weld together behind a cutting blade, that is, the opposite sides of the kerf become molten from the heat generated in the sawing operation and How together behind the blade. With my saw, of course, this cannot occur, for n 30 positively separates the opposite faces of a kerf for a substantial distance rearwardly of the saw blade 12.

Various changes and modifications may of course be made in the particular form of power saw illustrated and described herein without departing from the scope of my invention which should be limited only to the extent set forth in the appended claims. For example, though it might perhaps be somewhat more expensive, a power saw might be made in accordance with my invention in which the assembly, including n 3i?, guides 32, locking plates 4d, hold-down member 50 and tubular member 60 might be mounted for withdrawal into or through work supporting surface 11.

I claim:

l. A power saw of the reciprocating blade type comprising a work supporting surface, a fin extending upwardly therefrom, means -f-ree of any part extending above said work supporting surface for supporting said n, said lin supporting means being the sole support of any kind for said iin and said iin being of a thickness not substantially greater than the width of a kerf to be formed in a workpiece by the saw, a guideway supported above said work supporting surface solely by said n and adapted to guide the upper end of a saw blade, means below said work supporting surface for supporting the lower end of the saw blade, said saw blade being adapted to pass through the work supporting surface, and means beneath said work supporting surface for moving the blade supporting means in a vertical plane to impart a cutting motion to the saw blade, whereby a workpiece of unlimi'ted lateral extent in any direction may be cut by said saw.

2. A power saw according to claim l which includes a guard mounted on and supported solely by the fin t-o cover substantially any exposed portion of a saw blade above said work supporting surface.

3. A power saw according to claim l in which the guideway has a channel therein which extends longitudinally and vertically therethrough, the channel being adapted to receive a guiding element mounted in the upper end of a saw blade.

4. A power saw according to claim l which includes a work hold-down member secured to and supported solely by said fin.

5. A power saw according to claim 4 which includes means for adjustably mounting the hold-down member on the fin.

6. A power saw of the reciprocating blade type comprising a work supporting surface, a iin extending upwardly therefrom, said fin being of a thickness less than the width of a kerf to be formed in a workpiece by the saw, a .guideway supported on said lin above said work supporting surface and adapted to guide the upper end of a saw blade, said guideway comprising a pair of oppositely disposed guide members one secured to each side of the forward edge of the fin and each having a ver'- tically disposed groove `therein which in combination with the groove formed in the other forms a channel adapted -to receive a guiding element mounted in the upper end of the .saw blade, the upper end of .the blade itself being adapted to be received between said guide members, means below said work supporting surface for supporting the lower end of the saw blade, said saw blade being adapted to pass `through the work supporting surface, and means for moving the blade supporting means in a vertical plane yto impart `cutt-ing motion to `the saw blade.

7. A power saw according to claim 6 which includes blade guard and work hold-down means mounted on said fin and surrounding said guide members and the upper end of the saw blade.

8. A power saw according to claim 7 in which .the blade guard and work hold-down means are mounted on said fin for vertical adjustment.

9. A power saw of the reciprocating blade type comprising a work supporting surface, a iin extending upwardly therefrom, means free of any pant extending above said work supporting surface for supporting said n, said n supporting means being the sole support of any kind for said fin and said iin being of a thickness less than the width of a kerf to be 4formed in a workpiece by the saw, a guideway supported above said work supporting surface solely by `said n and adapted to guide the upper end or a saw blade, means below said work supporting surfa'ce for supporting the lower end of the saw blade, said saw blade being adapted to pass through the work supporting surface, and means' for moving the blade supporting means in a vertical plane to impart a cutting motion to the saw blade, whereby a workpiece of unlimited lateral eXtent .in any direction may be cut by said saw, said liin having a forward vertically disposed edge adapted to extend in a vertical direction in close proximity to the path of Itravel of the rear edge of a saw blade whereby said forward edge of the fin acts `as a backup for the saw blade during operation of the saw.

l0. A power saw according to claim 9 which includes a 'conventional hack saw blade, in which `the guideway is adapted to limit movement of the upper portion of said blade to a vertical straight line direction, and which includes guide means -for the supporting means for the lower end `of the blade which limits movement thereof and therefore movement of the lower end off the blade t0 a vertical straight line direction.

11. For use in a power saw of the reciprocating blade type including a work supporting surface, the combination of a fin adapted to be supported solely by and extend vertically `from said work supporting surface, said n having a thickness less than the width of a kerf to be formed in a workpiece by the saw, a guideway adapted to lie above said work surfa'ce to receive and guide the upper end of a saw blade mounted in the saw, said guideway Ibeing supported on and solely by said 1in, and blade guard and work hold-down means adjustably mounted on and supported solely by said fin substantially to surround said saw blade.

References Cited in the le of this patent UNITED STATES PATENTS 12,679 Hutchinson Apr. 10, 1855 139,426 Scholeld May 27, 1873 1,838,125 Wirtz Dec. `29, 1931 FOREIGN PATENTS 108,981 Switzerland Feb. 16, 1925 

